I'm programming in c# using opencv (emguCV). I use motion detection approach to detect some changes in a paper wall. For example it's may be colored by a laser pointer. My problem is that when I use motion detection, some unwanted changes are occurred by wind, sun and etc. Also I want to save the time of event so I can't use thresholding methods because they find point of laser totally, not their times. Is there any approach to filter mentioned effects?